Electric heating element.



T. M. GAVEN. ELECTRIC HEATING ELEMENT.

APPLIGATION FILED AUG.1, 1911.

2 SHEETS-SHEET 1.

Patented Oct.

T. M. GAVEN.

ELECTRIC HEATING ELEMENT.

APPLICATION FILED AUG.1, 1911.

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UNITED STATES PATENT OFFICE.

' T allwhom it may concern:

Be it known that I, TREVOR. ICAVEN, a

.. citizen of the United States, and resident tain new and useful Improvements in Electrie Heating Elements; and I do hereby declare that the following 'is a full, clear, and exact description thereof. I 1

My invention relates to that ty e of elec tric heating elements in each of w ich there is radiation from energized resistance through insulation of the same contained in a plate of refractory material to which a metallic surface plate may or may not be connected in intimate contact with the same and said insulation, said invention consisting in what is herein particularly set forth with reference to the accompanying drawings and pointed out-in the claim of,- this specification, its object being to economically increase efiiciencypf such an element by means of a peculiar resistance and insulation for the same.

Figure 1' of the drawings is a diagram illustrating a preferred disposition of a pair of resistance devices in a refractory plate of an electric-heating element, and a switch by which to employ said devices in multiple or series so as to vary the degree of heat emanating from said element; Fig. 2, a plan view partly in horizontal section illustrating fragments of the refractory plate, one of the resistance devices and insulation for the same in said plate; Fig. 3, a transverse sectional view, indicated by line 3 3 in Fig. 2,'and including a showing of a fragmentof a metallic surface plate in intimate contact with the refractory plate andinsulation aforesaid; Fig. 4, a plan view of a fragment of the aforesaid resistance device on an enlarged scale; Fig. ,5, a diagram 1llustrating a disposition of another form of resistance device in a refractory plate and the electric connections therewith; Fig. 6, a view similar to Fig. 2, illustrating the plaiting of a resistance ribbon in the second form of resistance device, and Figs. 7 and 8, sectional viewsrespectively indicated by lines 7--'7 and 8-8 in Fig. 6, a fragment of a metallic surface plate being included in Fig. 8.

Referring by numerals to the drawings, 9 indicates a refractory plate of molded as bestos or other suitable material provided I ELECTRIC HEATING ELEMENT.

or MILWAUKEE, wrscoivsxmnssielvon To A. J. LINDEMANN & HovEnsoN 00., or MILWAUKEE, WISCONSIN."

patentd fices; 1913'.

with recesses inward from one side/thereof more, resistance devices are embedded. This combination constitutes an electric heating element provided with a metallic surface plate 11 permanently secured'thereresistance devices 12, 133- are shown'as having one terminal of each inconnection with a contact 14 of a pole-changer'switch 15 that is coupled to binding-posts 16, 17 of positive and negative current wires. The other'terminal of the resistance device 12 is in permanent connection with a bindingpost- 18 to which a branch of the hegative current wire is also connected, and the other connection with a contact 1 1 cf-said switch. The arms of the pole-changer switch being set on the contacts 14, 14, the resistance positive current dividingat said-contact 14 to flow through both of said're'sistancedewith the resistance device 13. When the resistance devices are thus connected in multiple, the greatest degree of heat emanates from the herein described electric heating element, but if the switch be adjusted to connect the binding-post 16 with the contact 14 and break the connection between the binding post 17 and said contact, said resistance devices will be connected in said element. To obtain a medium degree of heat, the switch is adjusted to remain on contact 14: but be off contact 14 so that only the-resistance device 12 is in circuit. Other means may be employed in connection with the aforesaid resistance. devices for throwing one or both of the same into circuit, the general construction and disposition of parts as thus far described being common in the art to which my improvements pertain..

is flat and zigzag in the insulation 10, this insulation being a solidified plastic cement compound of high thermal conductivity designed to unite the refractory and metallic plates aforesaid. The insulation in its in .the refractory plate, and between this containing insulation 10 in whi'chpne or to in intimate contact with said refractory plate and insulation. In Fig.21xa pairof 3 terminal of the resistance device 13 is in vices to the negative current wire then temporarily connected, through said switch,

series to:obtain the least degree of heat from plastic state is subjected to a highpressure devices 12,13, are connected in multiple, the: i

Each of the aforesaid resistance elements I plate and the metallic plate, all the components of the improved electrical heating element being combined in a single solid mass, this being an important feature of my invention. 7

As shown in Figs. 2, 3 and 4, each resistance device may be a fiat stiff zigzag strip, and as shown in Fig. 4:, this strip being preferably slit at intervals thereof transversely from its edges for a portion of its width, the slits from one edge alternating with those from the opposite edge, whereby tortuosity of current travel is increased in order to provide for the utilization of a high percentage of the heat energy of said current.

The resistance device shown in Figs. 6,

7 and 8, is a zigzag strip 13 of resistance r ibbon laid flat in the aforesaid insulation,

the stretches of the ribbon being alternately upon different parallel planes, thereby forming a coreless Fig. 8, and the laying of said ribbon is such as to utilize the greatest amount of its surface for the distribution of heat energy.

In any form of resistance device or devices, the arrangement of the same with the insulation thereof is such as to provide for the greatest possible radiation from the heatiug element, the metal surface plate, being in fiat helix, as best shown in sectional area is the same at all points of the flat resistance strip or ribbon aforesaid.

I claim:

An electric heating element comprisinga plate of refractory material provided with recesses in its face, a solidified plastic insulating filler of highthermal conductivity for the plate recesses,the same forming a homogeneous mass with 'relation to said plate, a coiled resistance element embedded 7 within the plastic insulation, and a metallic surface plate in cohesive relation with the plate and insulation.

In testimony that I claim the foregoing I have hereunto set my hand at Milwaukeein the county of Milwaukee andState of Wisconsin in the presence of two witnesses.

TREVOR M. CAVEN.

Witnesses e JOHN S. BRENNAN, TM. L. PIEPLovv. 

